path: root/src/Geom2d/Geom2d_TrimmedCurve.cdl

-- File:	Geom2d_TrimmedCurve.cdl
-- Created:	Wed Mar 24 18:24:24 1993
-- Author:	JCV
--		<fid@sdsun2>
-- Copyright:	 Matra Datavision 1993

---Copyright:   Matra Datavision 1991, 1992





class TrimmedCurve from Geom2d inherits BoundedCurve from Geom2d

        --- Purpose :
        --  Defines a portion of a curve limited by two values of 
        --  parameters inside the parametric domain of the curve.
        -- The trimmed curve is defined by:
    	-- - the basis curve, and
    	-- - the two parameter values which limit it.
    	--  The trimmed curve can either have the same
    	-- orientation as the basis curve or the opposite orientation.

uses Ax2d     from gp,
     Pnt2d    from gp, 
     Trsf2d   from gp,
     Vec2d    from gp,
     Curve    from Geom2d,
     Geometry from Geom2d,
     Shape    from GeomAbs


raises ConstructionError   from Standard,
       RangeError          from Standard,
       NoSuchObject        from Standard,
       UndefinedDerivative from Geom2d,
       UndefinedValue      from Geom2d


is

  Create (C : Curve; U1, U2 : Real; Sense : Boolean = Standard_True)
     returns mutable TrimmedCurve
        --- Purpose :
        --  Creates a trimmed curve from the basis curve C limited between 
        --  U1 and U2.
        --  
        --  . U1 can be greater or lower than U2.
        --  . The returned curve is oriented from U1 to U2.
        --  . If the basis curve C is periodic there is an ambiguity 
        --    because two parts are available. In this case by default
        --    the trimmed curve has the same orientation as the basis
        --    curve (Sense = True). If Sense = False then the orientation
        --    of the trimmed curve is opposite to the orientation of the
        --    basis curve C.
        --  If the curve is closed but not periodic it is not possible
        --    to keep the part of the curve including the junction point
        --    (except if the junction point is at the beginning or
        --    at the end of the trimmed curve) because you could lose the
        --    fundamental characteristics of the basis curve which are 
        --    used for example to compute the derivatives of the trimmed
        --    curve. So for a closed curve the rules are the same as for 
        --    a open curve.
        -- Warnings :
        --  In this package the entities are not shared. The TrimmedCurve is
        --  built with a copy of the curve C. So when C is modified the
        --  TrimmedCurve is not modified
   	--  Warnings :
        -- If <C> is periodic, parametrics bounds of the TrimmedCurve, 
        -- can be different to [<U1>;<U2>}, if <U1> or <U2> are not in the
        -- principal period.
        -- Include :
        --  For more explanation see the scheme given with this class. 
    	--    Raises ConstructionError the C is not periodic and U1 or U2 are out of 
        --  the bounds of C.
        --  Raised if U1 = U2.
     raises ConstructionError;
     



  Reverse (me : mutable);
        --- Purpose :
        --  Changes the direction of parametrization of <me>. The first and
        --  the last parametric values are modified. The "StartPoint"
        --  of the initial curve becomes the "EndPoint" of the reversed
        --  curve and the "EndPoint" of the initial curve becomes the
        --  "StartPoint" of the reversed curve.
    	-- Example  -   If the trimmed curve is defined by:
    	-- - a basis curve whose parameter range is [ 0.,1. ], and
    	-- - the two trim values U1 (first parameter) and U2 (last parameter),
    	--   the reversed trimmed curve is defined by:
    	-- - the reversed basis curve, whose parameter range is still [ 0.,1. ], and
    	-- - the two trim values 1. - U2 (first parameter)
    	--   and 1. - U1 (last parameter).

  ReversedParameter(me; U : Real) returns Real;
	---Purpose: Returns the  parameter on the  reversed  curve for
	--          the point of parameter U on <me>.
	--          
	--          returns UFirst + ULast - U


  SetTrim (me : mutable; U1, U2 : Real; Sense : Boolean = Standard_True)
    	--- Purpose : Changes this trimmed curve, by redefining the
    	-- parameter values U1 and U2, which limit its basis curve.
    	-- Note: If the basis curve is periodic, the trimmed curve
    	-- has the same orientation as the basis curve if Sense
    	-- is true (default value) or the opposite orientation if Sense is false.
    	-- Warning
    	-- If the basis curve is periodic, the bounds of the
    	-- trimmed curve may be different from U1 and U2 if the
    	-- parametric origin of the basis curve is within the arc
    	-- of the trimmed curve. In this case, the modified
    	-- parameter will be equal to U1 or U2 plus or minus the period.
    	-- Exceptions
    	-- Standard_ConstructionError if:
    	-- - the basis curve is not periodic, and either U1 or U2
    	--   are outside the bounds of the basis curve, or
    	-- - U1 is equal to U2. 
     raises ConstructionError;
      


  BasisCurve (me)    returns Curve;
        --- Purpose : Returns the basis curve. 
        -- Warning
    	-- This function does not return a constant reference.
    	-- Consequently, any modification of the returned value
    	-- directly modifies the trimmed curve.


  Continuity (me)  returns Shape from GeomAbs;
        --- Purpose :
        --  Returns the global continuity of the basis curve of this trimmed curve.
        -- C0 : only geometric continuity,
        -- C1 : continuity of the first derivative all along the Curve,
        -- C2 : continuity of the second derivative all along the Curve,
        -- C3 : continuity of the third derivative all along the Curve,
        -- CN : the order of continuity is infinite.


  IsCN (me; N : Integer)   returns Boolean
        --- Purpose 
        --  Returns True if the order of continuity of the 
        --  trimmed curve is N. A trimmed curve is at least "C0" continuous.
        --  Warnings :
        --  The continuity of the trimmed curve can be greater than
        --  the continuity of the basis curve because you consider
        --  only a part of the basis curve.
     raises RangeError;
        --- Purpose :  Raised if N < 0.


  EndPoint (me)   returns Pnt2d;
	--- Purpose :
	--  Returns the end point of <me>. This point is the
	--  evaluation of the curve for the "LastParameter".


  FirstParameter (me)   returns Real;
        --- Purpose :
	--  Returns the value of the first parameter of <me>. 
        --  The first parameter is the parameter of the "StartPoint"
        --  of the trimmed curve.


  IsClosed (me)  returns Boolean;
        --- Purpose :
        --  Returns True if the distance between the StartPoint and
        --  the EndPoint is lower or equal to Resolution from package
        --  gp.


  IsPeriodic (me)   returns Boolean;
        --- Purpose : Returns true if the basis curve of this trimmed curve is periodic.


  Period (me) returns Real from Standard
    	---Purpose: Returns the period of the basis curve of this trimmed curve.
    	-- Exceptions
    	-- Standard_NoSuchObject if the basis curve is not periodic.
          raises
    	NoSuchObject from Standard
  is redefined;
  
  
  LastParameter (me)  returns Real;
	--- Purpose :
	--  Returns the value of the last parameter of <me>.
        --  The last parameter is the parameter of the "EndPoint" of the
        --  trimmed curve.


  StartPoint (me)  returns Pnt2d;
	--- Purpose :
	--  Returns the start point of <me>.
	--  This point is the evaluation of the curve from the 
	--  "FirstParameter".

        --- Purpose  : value and derivatives
        --- Warnings :
        --  The returned derivatives have the same orientation as the
        --  derivatives of the basis curve.


  D0 (me; U : Real; P : out Pnt2d)
     raises UndefinedValue;
        --- Purpose:
        --  If the basis curve is an OffsetCurve sometimes it is not 
        --  possible to do the evaluation of the curve at the parameter
        --  U (see class OffsetCurve).


  D1 (me; U : Real; P : out Pnt2d; V1 : out Vec2d)
     raises UndefinedDerivative;
        --- Purpose : Raised if the continuity of the curve is not C1.


  D2 (me; U : Real; P : out Pnt2d; V1, V2 : out Vec2d)
     raises UndefinedDerivative;
        --- Purpose : Raised if the continuity of the curve is not C2.


  D3 (me; U : Real; P : out Pnt2d; V1, V2, V3 : out Vec2d)
     raises UndefinedDerivative;
        --- Purpose : Raised if the continuity of the curve is not C3.
        

  DN (me; U : Real; N : Integer)  returns Vec2d
        --- Purpose  : For the point of parameter U of this trimmed curve,
    	-- computes the vector corresponding to the Nth derivative.
    	-- Warning
    	-- The returned derivative vector has the same
    	-- orientation as the derivative vector of the basis curve,
    	-- even if the trimmed curve does not have the same
    	-- orientation as the basis curve.
    	-- Exceptions
    	-- Standard_RangeError if N is less than 1.
    raises  UndefinedDerivative,
                   RangeError;


        --- Purpose : geometric transformations

  Transform (me : mutable; T : Trsf2d);
        --- Purpose : Applies the transformation T to this trimmed curve.
    	-- Warning The basis curve is also modified.

  TransformedParameter(me; U : Real; T : Trsf2d from gp) returns Real
	---Purpose: Returns the  parameter on the  transformed  curve for
	--          the transform of the point of parameter U on <me>.
	--          
	--          me->Transformed(T)->Value(me->TransformedParameter(U,T))
	--          
	--          is the same point as
	--          
	--          me->Value(U).Transformed(T)
	--          
	--          This methods calls the basis curve method.
     is redefined;  

  ParametricTransformation(me; T : Trsf2d from gp) returns Real
	---Purpose: Returns a  coefficient to compute the parameter on
	--          the transformed  curve  for  the transform  of the
	--          point on <me>.
	--          
	--          Transformed(T)->Value(U * ParametricTransformation(T))
	--          
	--          is the same point as
	--          
	--          Value(U).Transformed(T)
	--          
	--          This methods calls the basis curve method.
     is redefined;  



  Copy (me)  returns mutable like me;
---Purpose:
-- Creates a new object, which is a copy of this trimmed curve. 
    
fields

    basisCurve : Curve from Geom2d;
    uTrim1     : Real;
    uTrim2     : Real;

end;